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Sep 05, 2023

MXA LOG BOOK: SECRETS OF THE 2017 HONDA CRF450

The 2017 Honda CRF450 is as radically different from the 2016 model as the

The 2017 Honda CRF450 is as radically different from the 2016 model as the ill-fated 2009 CRF450 was from the highly regarded 2008 model. For eight long years the Honda engineers had lost their way. From a design point of view, two roads diverged in a yellow wood, and they took the one less traveled. Suffice it to say, it was the wrong road in terms of handling, suspension and powerband. Sales suffered. Honda's reputation took a nosedive, and new challengers arose while the brand was in the doldrums. It has been a long wait, but finally Honda can see the light at the end of the tunnel. One thing we know for sure—the 2017 Honda CRF450 makes the 2016 Honda obsolete. And that if you follow MXA's advice, you can turn your 2017 into a 2018 CRF450. And most of this advice, short of the map, stiffer springs and electric starter, are applicable to the 2018 CRF450.

The MXA wrecking crew has spent the last eight months testing every aspect of the new CRF450 (remember, we got our 2017 CRF450 several months before they were in the showrooms). What follows is a chronicle of the changes we made to our CRF450. We worked with the brightest people at Honda and the aftermarket world to attempt to solve every problem, no matter how trivial. We offer this as a racer's guide to the 2017 Honda CRF450.

We destroyed both radiators in 30 hours of racing—and not from crashing. It's important to note that the MXA wrecking crew raced its CRF450 every week. We don't think that a professional practice rider would suffer the same amount of damage. Why not? Racing takes a bigger toll on the radiator vanes than play riding, because racers have no choice but to follow in the roost of other riders. The inherent problem with Honda's radiators is that the vanes on the CRF450's radiator guards are so widely spaced that they direct roost and rocks into the radiators instead of blocking them. The finning on our radiator cores looked like someone had been hitting it with a tap hammer. Most of the fins were dented closed. The fix, albeit two expensive radiators later, was Twin Radiator sleeves. Twin Air's mesh-like screens knock down the hard stuff without obstructing airflow.

MXA's test bikes are typically used in long motos, with big hills and heavy loads on the engine. Under these conditions, not to mention SoCal's hot weather, we spewed water on several occasions. Our CRF450 ran hot. How did we fix it? The simplest and cheapest way to avoid boiling your engine, especially important on over-stressed cooling systems, is to drop-kick the stock 1.1 kg/cm2 radiator cap for a 1.6 kg/cm2 or higher cap. Raising your cooling system's maximum operating pressure raises your cooling system's boiling point, and therefore helps avoid boil-over; however, it does not lower the engine's operating temperature prior to boil-over. It simply allows your engine to continue to operate at temperatures higher than what the stock 1.1 kg/cm2 cap allows. Water boils at 212 degrees, and for each pound you raise the system's blow-off pressure, you raise the boiling point 3 degrees. A 1.1 kg/cm2 cap converts to 15.6 psi. A 1.6 kg/cm2 cap converts to 22.7 psi. Most factory race bikes and stock KTMs use 1.8 kg/cm2 caps, which are 25.6 psi. We took the overwhelmed 1.1 kg/cm2 radiator cap off of our 2017 Honda CRF450 and put on a stiffer 1.6 kg/cm2 cap. This raised the boiling point to 233 degrees.

The big news on the suspension front is that for 2017 Honda abandoned air forks and returned to a coil-spring system. Nevertheless, in stock trim, the Showa forks are too soft for fast riders and too harsh for slow riders. No surprise here, as the last coil-spring CRF450 fork also had soft fork springs. Forks that are too soft for fast riders but too harsh for slow riders are the hardest to fix because the obvious solution for one issue is calamity for the other. Of course, you can send your forks out to your favorite suspension guru to have them re-valved, but the simplest solution is to replace the stock 0.48 N/m fork springs with the stiffer, optional 0.50 N/m fork springs. This is a very good fix, because the stiffer fork springs help fast riders with their bottoming issues, and, conversely, the stiffer fork springs hold the fork higher in its stroke, allowing much softer compression damping settings for slower riders. It was a win-win. Our Pro test riders ran the compression on 11 clicks out and the rebound on 9 clicks out. Intermediate test riders ran both the compression and rebound on 11 clicks out. Vet and Novice test riders went with 13 clicks. It should be noted that fast racers can raise the oil height by 10cc and slower riders can lower the oil height by 10cc.

Our best fix, and also considerably more expensive, was to switch to the WP Cone Valve forks and Trax shock that we also ran on our 2016 Honda CRF450. The WP Cone Valves forks work as well on a Honda as on a KTM.

Honda's brakes perform adequately, but the wrecking crew made two changes: First, we drained the stock brake fluid. It is a low-temp mixture that feels spongy at the lever and fades under hard braking. We replaced it with Maxima 600 Series brake fluid. You can run your favorite brand, but make sure that it has a minimum dry boiling point of 600 degrees Fahrenheit (316 degrees Celsius). This will ensure fade-free operation. Second, remove the front and rear disc guards. In our opinion, disc guards hinder airflow to the rotor, calipers and pads, which makes the battle against brake fade more difficult.

To expand our knowledge base, after spending time on the kick-start version, we switched our CRF450 to electric start. Honda offers a kit—although, you need to buy the wiring harness and battery separately—to achieve this. Once we had the kit installed, it worked flawlessly, but there are things you need to know. Here is a quick list.

INSTALLATION TIME: It took our Honda mechanic five hours of labor to install the kit. Honda claims a 3.5-hour installation time, but many shops are taking much longer than five hours. You can do it yourself, but unless you are a certified mechanic, you can expect it to take around eight hours or more. If you have doubts about your mechanical skills, it's best to have your local shop do it for you, but it could cost you $500 or more in labor.

KICK-STARTER: You have the choice of leaving the kick-starter on your CRF450, along with adding the electric-starter kit. We chose to eliminate the kick-starter and its associated gears because of weight. We have abundant experience with KTM electric starters and do not live in fear of them failing.

AGM BATTERIES: Honda does not supply a battery with the electric starter kit; if Honda did, it would be a Yuasa lead-acid battery that would weigh almost 5 pounds. We elected to run an AGM battery. AGM stands for "Absorbed Glass Mat." It is lighter than a lead-acid battery, even though it is a lead-acid battery. How can that be? AGM batteries have woven glass mats between the battery plates. AGM batteries contain only enough liquid to keep the mat wet with the electrolyte. They are non-spillable, deep-cycle, low-self-discharge batteries that can be mounted in any position, including upside down. They may be lighter than a normal lead-acid battery, but they are not as light as the lithium-iron phosphate batteries that KTM uses. We chose it because we were unsure how much energy the CRF450 would need to start on a cold day—and we didn't want to come up short on cranking power.

LITHIUM-IRON PHOSPHATE BATTERIES: Lithium-iron phosphate batteries (also called "LiFePO4" or "LFX" batteries) are the best choice for riders trying to save weight. Don't confuse a lithium-iron phosphate (LFX) battery with a lithium-ion battery (more specifically, a lithium cobalt-oxide battery). Lithium-ion batteries are most commonly used in computers, cameras and phones. A lithium-iron phosphate battery has a higher resistance to thermal runaway, longer calendar life, quicker recharge rate, five times as many available discharge cycles, a higher peak-power rating and costs less than a lead-acid battery. But, the most important fact about LiFePO4 batteries is that they are light. They can easily save 3 pounds over a lead-acid battery. In time, we will switch from our AGM battery to a lithium-iron phosphate battery to save weight.

WEIGHT: The 2017 Honda CRF450 hits the scales at 233 pounds without fuel in the tank. Honda's optional electric-start kit will add anywhere from 7–10 pounds (depending on which battery you choose to run). In the simplest terms, an electric-start Honda CRF450 will weigh at least 240 pounds.

CLUTCH LEVER: The Honda kit comes with a new clutch perch that is equipped with a micro-switch that will not allow the electric starter to turn over unless the clutch lever is pulled in. This seems to be a lawyer-driven concept—out of fear that errant riders will launch themselves through garage doors by accidentally hitting the start button. But, if you want to run an aftermarket clutch perch, this is a problem. If you must run your favorite clutch perch, you can splice the two wires going to Honda's micro-switch clutch perch together to bypass its cut-off switch. It should be noted that KTM electric starters are always on.

If you run the electric starter, the bulkiness of the battery will cut down on airflow to the engine (the kit comes with the CRF450RX enduro bike battery tray). To combat this, MXA super glues a 3/8-inch rubber bumper to the back of the seat base. The bumper raises the rear of the seat up off the rear fender, even when you are sitting on it, to allow extra air to flow down into the airbox.

MXA glues this rubber spacer to the bottom of the seat with Super Glue. Why, you ask? To help the airbox flow more air around the battery.

On several occasions MXA test riders had the front of the seat come unhooked. When we landed hard on the seat, the middle section flexed so much that the front hook popped out. Additionally, when the seat pulls out, the gap between the seat and the bodywork often causes the rider's thigh to get pinched between the two. Test riders always made sure to push the seat as far forward as possible and weight the saddle before tightening the seat bolts.

Every MXA test rider had issues with the clutch. Here were the problem areas:

(1) The 2017 Honda CRF450 uses a judder spring and plate. What is a judder spring? On Honda's seven-plate CRF450 clutch, the seventh plate is narrower and pressed against a ring-like Belleville washer. The purpose is to lightly preload the clutch plates to lessen chatter when the clutch is first released. MXA has never liked the judder-spring concept. It not only leads to breakage of the narrow judder plate, it turns the CRF450's seven-plate clutch into a 6-1/2-plate clutch. We remove the judder spring and the judder plate and put in a full-size seventh plate. This offers better bite and longer life.

(2) With only 6-1/2 clutch plates, Honda had to run stiffer clutch springs (fewer plates require stiffer springs); however, the spring pressure on the seven plates is barely adequate for clutch abusers. We added stiffer Pro Circuit clutch springs (with some test riders preferring to run three stiff springs with three stock springs).

(3) Most test riders complained that the clutch released too far out on the lever's play. This meant that the riders were modulating the clutch at its engagement point with the tips of their fingers. We wanted to test aftermarket clutch perches, but since we ran the optional electric-start system, we had to run the micro-switch-equipped Honda clutch perch.

Inside the stock clutch, there are seven friction plates. It is important to note that these seven plates are sub-divided into three different types of fiber plates. Starting from the inside of the clutch basket, the first plate is the judder spring plate. It is easily recognized because the fiber surface of the judder plate is notably narrower than the other six plates (as mentioned above, we removed the judder plate and the judder spring and replaced them with a normal friction plate). After the judder plate, there are five regular clutch plates (six if you replaced the judder plate). Finally, the outer plate has different dimensions from the other six plates. This final plate goes against the clutch's pressure plate on the outside of the stack.

The 2017 CRF450 has a herky-jerky power delivery at tip-in. This erratic power delivery turns quarter-throttle solutions in corners into a series of unsyncopated lurches with each blip of the throttle. MXA test riders found that the best way to avoid the sporadic low-end power delivery of the 2017 engine was to run the engine harder and higher in the rpm range. This worked well for fast riders, but not for Novice and Vet riders. Given that the Honda CRF450 works best in the midrange and well above its cranky low end, we geared it down one tooth (from 49 teeth to 50 teeth). This helped slower riders ride the bike higher in the powerband at low speeds in ruts and off-throttle flat turns and enhanced the pick up for fast riders. Every test rider preferred the 50-tooth over the 49 for general racing.

The stock rear chain guide has a two-piece rubber glide block inside the aluminum carrier. The previous CRF450s had a one-piece glide block. The problem with the two-piece glide block is that it flaps around and drags against the sides of the rear sprocket. Mechanically, it's not an issue, but cosmetically, it scratches the sides of the rear sprocket and leaves ugly drag marks, especially on anodized sprockets. The quick fixes are to super glue the 2017 chain block to the inside of the aluminum chain guide or order last year's chain block from your friendly local Honda dealer. We elected to replace the complete chain guide with a TM Designworks Factory Edition SX chain guide. It is almost indestructible, comes in several colors (we chose red) and is a replace-it-and-forget-it product.

To make Honda's Deltabox aluminum chassis more resilient longitudinally, we spent several days testing different motor mounts, head stays and engine bolts. In the end, we had our best luck making the Honda feel more absorbent by removing the two rear fuel tank bolts and the two exhaust pipe bolts where the pipe mounts to the subframe. In essence, this softens up the chassis. You would think that this would be imperceptible from the saddle, but it makes a difference. Think of it this way: the major difference between a KTM and a Husqvarna is that the Husky has a three-piece plastic airbox/subframe that flexes. Most test riders feel that the Husky offers a more comfortable ride than the KTM, even though they share everything but the plastic subframe. We are trying to achieve the same thing with the CRF450 frame.

Honda also recommended that we run the CRF450RX head stays (and suggested changing to some tapered motor mounts bolts that Geico Honda team has used in the past) to make the frame more forgiving..

Every fuel-injected Honda CRF450 has been prone to flame-out. Flame-out is when roll you the throttle off to get slowed down and the engine goes "poof" and quits running. Flame-out was a major issue on the 2009–2012 CRFs, but has been less of an issue since then. If you have trouble with flame-out, and we have even seen Cole Seely's works CRF450 suffer flame-out issues during the 2017 Supercross series, we suggest turning the idle up to help keep the engine percolating at low speeds. How do you do that? On the left side of the engine, behind the valve cover and tucked out of sight behind the frame, is a yellow plastic knob. When this yellow knob is pushed inward, it acts as an idle-adjustment screw. Turn it counterclockwise to speed up the idle and clockwise to slow the idle down. Make sure that the engine is warmed up before making any idle adjustments.

Although the 2016 CRF450's separate engine and transmission oil compartments were technically superior, they were hampered by the small quantity of oil contained in each compartment. For 2017, Honda has dropped the dual-oil concept and now mixes the engine and transmission oil together, just like on every other 450 four-stroke. For long-term Honda owners, this means that you have to change your engine oil at much shorter intervals than before. Additionally, don't forget to constantly check the crankcase breather tube. It is a transparent tube that exits on the front of the airbox. This clear tube captures overflow oil and needs to be drained when it fills up with oil. There is a rubber plug on the end of the breather tube that you remove to get excess oil out.

We did suffer considerable head-shake at speed, but this was largely caused by the soft front fork springs, which allowed the front to drop. This drop steepened the head angle and brought on unwanted oscillation. Stiffening the front fork springs lessened this; however, if you still feel that the 2017 CRF450 is unstable at high speeds or across rough ground, you can reinstall the HPSD from last year's bike. The mounting points are included on the 2017 bike, although the damper isn't.

The 2017 CRF450 has a stinkbug stance, which has been a common trait since 2009. We put the race sag at 107mm and slid the fork legs up in the clamps by 2.5mm. This lowered the overall bike height while maintaining the same frame geometry. Had we just lowered the rear, it would have kicked the head angle out and slackened the geometry. The 2017 CRF450 has the most sensitive fore/aft balance that we have ever encountered. Any change to the shock seriously affected the forks. Additionally, the shock's high-speed damping was already so far out that it only offered the ability to slow it down. The rear end moved up and down too much and tended to wallow in consecutive bumps. We switched from the stock 54 N/m shock spring to a stiffer 56 N/m shock spring. This was a big plus for riders over 170 pounds. Riders lighter than that can keep the stock shock spring. Stiffening up the rear end made the stock shock feel more stable in the rough. Pro, Intermediate and Vet riders ran the exact same low-speed compression (17 clicks out) and rebound (7 clicks out) settings. High-speed compression varied from 3.75 turns out to 3.5 turns out.

Getting more power out of the 2017 Honda CRF450 is easy. We tested exhaust systems from Pro Circuit and FMF, and both boosted power by at least two ponies. We even added a Pro Circuit race piston and gained an additional two horses on top of the 2 horsepower from the exhaust system. The pipe and piston produced a 62-horsepower CRF450 with gains all across the board, but the biggest improvement came from 8500 rpm to sign-off at 11,500 rpm. Torque went up 1 foot-pound (from 35.77 to 36.89 foot-pounds), with the biggest gains from low to mid. When you combine the pipe, piston and mapping, you get a very powerful machine that is phenomenal through the mid-range with peak power at 10,000 rpm.

It's no secret that some 2017 Honda CRF450s have suffered breakages of the automatic decompression system and cracked engine cases (on the right side of the engine). This isn't idle gossip, since the MXA wrecking crew was present when several CRF450s had mechanical issues, including one bike that cracked its cases at Honda's Monster Mountain press intro. MXA's CRF450 had the intake valves go out of adjustment very early in the program, seriously affecting low-to-mid performance.

Plus, the grips on our CRF450 weren't glued on tightly. They fell off.

There are three ignition maps accessible via the switch on the left side of the handlebars—stock (one blue flash that repeats three times), mellow (two blue flashes that repeat three times) and aggressive (three blue flashes that repeat three times). You can cycle through the three maps by pressing the button and holding it for one second (be sure the idle-adjuster knob is pushed in or the maps won't change). Every MXA test rider chose to run the stock map (one blue flash). There is no Launch Control button.

You can remap your 2017 Honda CRF450 with Honda's PGM-FI tuning kit. This kit, which includes software and a plug-in wiring module, allows a rider to use an IBM computer to alter multiple cells in both the fuel and ignition maps. In essence, the new software overwrites the ECU's base maps and can alter the percentage of fuel delivered, and advance or retard the ignition timing (1 degree at a time). The problem for the average rider is that the PGM-FI tuning kit is expensive to buy and complicated to use. Plus, as Honda updates it from year to year, you need new software as models change from year to years. So, in most cases, reprogramming the 2017 Honda CRF450 map is best left to your dealer or local hop-up shop.

We went straight to the source and had Honda's test department meet us at the track to allow us to test 10 different maps. We had three test riders with varying degrees of skill—from Pro to Vet—ride the bike. In this blind test, all three riders chose the exact same map combinations. We have included a screenshot of both the ignition and fuel maps that we are running to show you the direction to go. You will note that we didn't change any of the cells in the fuel map and concentrated mostly on retarding the ignition map.

We know that you think that print magazines are dead and that the internet will fill the void, but most of the stuff in every issue of MXA doesn't appear on the web for almost two months—if at all. Luckily, you can get all of MXA on your iPhone, iPad, Kindle or Android by going to the Apple Store, Amazon or Google Play. Better yet get the Digital desktop version at https://hi-torque.com/product/motocross-action-digital-edition/ for $9.99 a year.

The MXA test riders prefer the print version and not just because it is delivered by a uniformed employee of the U.S. Government, but because right now you can get 12 issues for $19.99 and a free $25 Gift Card from Rocky Mountain ATV/MC. That means that there is a profit to be made in this deal for you. For the Print magazine you can click on the yellow box below or go to: https://hi-torque.com/product/motocross-action/